Health impacts of air quality

Key points

PM10 concentrations decreased between 2006 and 2012. Using modelling, this reduction was associated with an estimated:

14 percent fewer premature deaths from exposure to human-made PM10

15 percent fewer hospital admissions from exposure to human-made PM10

9 percent fewer days of restricted activity from exposure to human-made PM10.

The decrease in estimated health impacts occurred despite an increase in the population.

The health impacts are modelled and are not determined from hospital records. Modelling is a common approach used to estimate health impacts from air quality and different modelling approaches exist. The estimates are determined from the PM10 concentrations the population is exposed to and the probability of the health risks being experienced at these concentrations. These health risks have been determined from international and national population studies.

The model used was developed to estimate health impacts in New Zealand. The methodology used for these estimates is consistent with international practice and has been internationally and nationally peer reviewed. Other methodologies for estimating health impacts from air quality also exist.

PM10 and health

The health impacts from air quality focus on those caused by exposure to PM10. This is because PM10 is associated with a range of effects, from minor irritation to more severe impacts, and it is the pollutant that most often breaches the national short-term standard and exceeds the World Health Organization long-term guideline. We have a good understanding of the concentrations of PM10 experienced in New Zealand, and epidemiological evidence about the health risks is well established.

As PM10 is a collection of pollutants, such as metals, nitrates, sulphates, and organic matter, the health impacts are from more than one type of pollutant and provide a broader assessment of health impacts. The health impacts from PM10 or PM2.5 (which is a component of PM10) are the most commonly assessed by other countries as they are seen as the air pollutants of greatest concern. While other air pollutants may have adverse health impacts and are not captured in the measures below, the majority of health impacts in New Zealand are associated with PM10 (Kuschel et al, 2012).

The health effects associated with exposure to PM10 are diverse, ranging from very subtle effects to premature mortality. People with existing health conditions, the young, and older people are more vulnerable to these effects.

National indicator: Estimated health impacts from human-made PM10 down from 2006

The estimated health impacts (using modelling) from exposure to human-made PM10 decreased from 2006 to 2012 in all three categories.

Estimated premature deaths decreased from 1,170 to 1,000 (down 14 percent). This equates to about 3 percent of the total deaths in New Zealand that year.

Estimated hospital admissions for cardiac and respiratory conditions due to exposure to PM10 decreased from 610 to 520 (down 15 percent).

Estimated restricted activity days in which symptoms were sufficient to prevent usual activities, such as work or study, decreased from 1.49 million to 1.35 million (down 9 percent).

These decreases in estimated health impacts occurred despite an increase of 200,000 in New Zealand’s population between 2006 and 2013.

Information on the estimated health impacts of human-made PM10 is important because it is possible to manage its sources.

These estimated health impacts are associated with exposure to PM10, but PM10 is not necessarily the sole cause of the estimated health impact as other factors may be involved. For example, exposure to PM10 can aggravate existing conditions such as asthma, which is not caused by exposure to PM10, but can result in hospital admissions. In this example, it is the combination of another factor (a pre-existing condition) with exposure to PM10 that produces the estimated health impact.

The estimate of hospital admissions is lower than the number of premature deaths, as hospitalisations exclude cases leading to premature death.